Antinociceptive activity of niga-ichigoside F1 from Rubus imperialis.

This work describes the antinociceptive effect of a triterpene glycoside, niga-ichigoside F1 (1), obtained from an EtOAc extract of the aerial parts of Rubus imperialis. When evaluated against an HOAc-induced writhing model, it exhibited an ID(50) value of 3.1 mg/kg (ip). Moreover, in a formalin-induced pain model, both phases of pain were inhibited by compound 1, with ID(50) values of 2.6 (first phase) and 2.7 (second phase) mg/kg, (ip), respectively.